The invention relates to a friction-susceptible component, for instance, a component of a thermal turbo machine.
In the description of the background of the present invention that follows reference is made to certain structures and methods, however, such references should not necessarily be construed as an admission that these structures and methods qualify as prior art under the applicable statutory provisions. Applicants reserve the right to demonstrate that any of the referenced subject matter does not constitute prior art with regard to the present invention.
The guide and rotor blades of gas turbines are subject to large loads. To minimize leakage losses of the gas turbine, the rotor blade of the gas turbine is fitted with a very small clearance to the stator, resulting in a brushing contact. The stator of the gas turbine is provided with a honeycomb structure. The honeycomb structure consists of a thermally resistant metal alloy. In another variation, smooth, coated, or uncoated heat-accumulating segments (WSS) are provided radially opposite the rotating blade on the outer radius. The blade tip then brushes against these heat-accumulating segments. To prevent the blade tip itself from being abraded, it can be coated so that the heat-accumulating segments are abraded to a greater degree. But the disadvantage of this embodiment is that the coating has only limited adhesion to the turbine blade. It is also a disadvantage that the drilled cooling air openings that may be provided on the heat-accumulating segment and/or on the blade are obstructed during the rubbing.
Documents DE-C2 32 35 230, EP-132 667 or DE-C2-32 03 869 disclose the insertion of metal felts at various locations of gas turbine components, for example at the tip of a turbine blade (DE-C2-32 03 869), between a metal core or a ceramic outer skin (DE-C2 32 35 230) or as a jacket of the turbine blade (EP-B1-132 667). But these designs have the disadvantage that the inserted metal felt does not have a sufficient oxidation resistance. Increases in hot gas temperatures, as in modern gas turbines, require that the materials used must fulfill ever-increasing requirements. The metal felts in the cited documents do not fulfill the requirement for current specifications, in particular, in relation to a necessary mass of oxidation resistance.
It is the objective of the invention to overcome these and other disadvantages. The invention realizes this objective by creating a component of a thermal turbo machine with a sufficient mechanical strength and constant cooling action at friction-susceptible locations.
According to one aspect of the invention, there is provided a friction-susceptible component of a thermal turbo machine arranged on a rotor or a stator of the thermal turbo machine, the component comprising an intermetallic felt at the friction-susceptible locations.
By selecting the composition of the intermetallic felt properly, the material has sufficient strength, oxidation resistance and plasticity. Another advantage is created when the intermetallic felt is coated with a ceramic material, since a very good adhesion of the ceramic material is achieved on the rough surface of the intermetallic felt. This provides, for example, the tip of the guide or rotor blade with good protection against thermal and friction-initiated effects. Another advantage is created in that drilled cooling air openings are not obstructed by abrasion during the operation since the material is porous.